So I was playing through some TT problems and I felt a bit of deja vu. I brushed it off at first, but then I swore I started seeing the same problem over and over. I was sure that this wasn't the same TT#  problem, however.

Through a little bit of research, I've discovered that Tactics Trainer problems #0041764 through # 0041771 are indeed all the same problem. Have a look for yourself.

http://www.chess.com/tactics/problems.html?code=0041764

http://www.chess.com/tactics/problems.html?code=0041771

And all the ones in between are the same position, same side to move, same moves. Is there a reason for having so many duplicates of this problem, or is this an error?

I imagine with a site this large two repeats are well within the acceptable range of errors.

No no no, ALL of the problems between #41764 and #41771 are identical. That's eight copies, not two.

Thank you for reporting these duplicate tactics trainer problems. I have now removed the duplicates.

I think this has happened to me before a couple of times.